1. Field of the Invention
The present invention relates to a floating caliper type disc brake device suitably adapted for heavy vehicles such as a commercial vehicle, and in particular to a torque member which forms an essential part of the disc brake device.
2. Description of Related Art
A disc brake device clamps a disc rotor which is rotated together with a rotating body to be braked, on both sides of the disc rotor in the axial direction of the latter, with a pair of brake pads so as to brake the disc rotor.
Furthermore, the pair of brake pads are circumferentially held in brake pad supporting parts of a torque member so as to be displaceable in the axial direction of the disc rotor while the torque member is attached to a vehicle body at its one side in the axial direction of the disc rotor so as to receive a torque which is transmitted thereto from the disc rotor through the brake pad supporting parts upon braking.
It is noted that the pressing of the pair of brake pads against the disc rotor is carried out by a caliper which is supported on the above-mentioned torque member so as to be displaceable in the axial direction of the disc rotor in the case of a floating caliper type disc brake device.
By the way, in the case of a floating caliper type disc brake device for a heavy vehicle, the energy to be braked is large. Accordingly, a torque transmitted to the torque member from the disc rotor through the brake pad supporting parts is also large, so that it is required to enhance the rigidity of the torque member.
In order to enhance the rigidity, it has been conventionally proposed, as disclosed, for example, in Japanese Patent Laid-Open Publication No. 55-44,200, to take the following countermeasure for the torque member.
That is, as shown in FIG. 5, a torque member b attached at its part a to the vehicle body and supporting a caliper which is not shown and which is floatable in the axial direction of a disc rotor by means of a pin guide mechanism planted in a part c, includes brake pad supporting parts d and bridge parts e each of which couples two of the brake pad supporting parts d opposed in the axial direction of the disc rotor, and which are connected to together by a cross-linking part f laid along the outer periphery of the disc rotor, thereby the above-mentioned counter measure for the torque member b can be made.
The brake pad supporting parts d on the outer side remote from the vehicle attached side, is subjected to a force indicated by arrow .alpha. when a torque is transmitted to the brake pad supporting parts d from the disc rotor upon braking, and this force .alpha. causes the brake pad supporting parts d to be displaced in the rotating direction of the disc rotor.
Since the bridge parts e are coupled therebetween with the cross-linking part f in the above-mentioned conventional torque member b, the above-mentioned outer side brake pad supporting parts d can be restrained at their outer end parts in the radial direction of the disc rotor from being displaced even by the force .alpha..
However, the inner end parts of the outer side brake pad supporting parts d in the radial direction of the disc rotor is not given with a sufficient restraining force even by the cross-linking part f, and accordingly, they are displaced by the force .alpha. in the same direction as that of the latter, that is, in the rotating direction of the disc rotor, and further, a mouth opening deformation in a direction indicated by arrow .beta. is unavoidable.
Thus, the conventional torque member b is likely to incline the outer brake pads, causing uneven wear of the outer brake pads.
Further, since the cross-linking part f is laid along the outer periphery of the disc rotor, it has been proposed that it degrades the cooling ability of the disc rotor, and further, the assembling ability of the disc brake device is deteriorated due to the following reasons.
That is, when the disc brake assembly is to be attached to the chassis of a vehicle body, opposite brake pads are spaced from one another by an elastic spacer having a thickness larger than that of the disc rotor and previously interposed between the opposite brake pads, and in this condition, the disc brake assembly is simply fitted from above onto the disc rotor which has been incorporated in the chassis, so as to expel the elastic spacer between the opposite pads by the disc rotor. Thus, it is usual to enhance the assembling ability of the disc brake assembly to the chassis.
However, in the conventional disc brake device, since the cross-linking part f is laid along the outer periphery of the disc rotor, the above-mentioned elastic spacer cannot be removed from the space between the brake pads. Accordingly, the above-mentioned assembling process cannot be used, and as a result the disc brake device is more difficult to assemble.